Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "The Messenger of Allah (peace and blessings be upon him) prayed inside the Ka'bah," while Bilal and al-Fadl (may Allah be pleased with them both) were at the door. Bilal (may Allah be pleased with him) said: 'He (peace and blessings be upon him) prostrated,' and al-Fadl (may Allah be pleased with him) said: 'He (peace and blessings be upon him) bowed.'
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11187